Free radical polymerization using acidified ethoxylated conjugated fatty ether surfactants

ABSTRACT

The free radical initiated addition polymerisation of ethylenically unsaturated, particularly acrylic monomers in which the dispersed phase is stabilised by a surfactant including at least one anionic surfactant compound of the formula (I): R 1 -(OA) n -X where R 1  is C 16  to C 22  hydrocarbyl including at least two double bonds; OA is oxyalkylene group; n is from 2 to 60; and X includes at least one acidic H atom, and is particularly a phosphate ester group, or a salt thereof, is described. The use of the surfactants of the formula (I) enable efficient emulsification and thus polymerisation at temperatures above those at which non-ionic unsaturated surfactants are effective. The polymer latex products give polymer films having good water resistance properties.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of U.S. Ser. No. 10/123,527,filed Apr. 17, 2002, which is further a continuation of U.S. Ser. No.09/597,066, filed Jun. 20, 2000, now abandoned, which is the nationalphase of International Application No. PCT/GB98/03829, filed Dec. 18,1998, which designated the United States and was published in English.These applications, in their entirety, are incorporated herein byreference.

[0002] This invention relates to the free radical initiated additionpolymerisation of unsaturated monomers in the presence of surfactantsincluding anionic non-migratory surfactants, in particular emulsionpolymerisation methods using such surfactants and specifically to themanufacture of acrylic polymers by oil-in-water emulsion polymerisationmethods using such surfactants.

[0003] PCT published Application No WO/13849 A describes fatty alcoholethoxylates of certain unsaturated alcohols and their use as surfactantsin oil-in-water emulsion polymerisation methods. The unsaturatedalcohols described are conjugated doubly unsaturated fatty alcoholsderived from linoleyl alcohol. Conjugated double bonds are said to aidincorporation of the surfactant in the polymer making the surfactantnon-migratory. Whilst these compounds can be effective, their use islimited because they are not effective surfactants at the temperaturesusually used in emulsion polymerisations. In the polymerisation Exampleof W0/13849 A a “conjugated linoleyl” 10-ethoxylate is used in anemulsion polymerisation run at 30° C., whereas commercial thermallyinitiated emulsion polymerisations are typically run at from 50 to 100°C., usually 60 to 90° C. The use of lower temperatures results insignificantly lower polymerisation rates thus drastically reducing theproductivity of the reaction. Operation at higher temperatures might bepossible by using much higher levels of ethoxylation, but this reducesthe weight efficiency of the surfactants and may have deleteriouseffects on the polymerisation or on the polymer emulsions in use. Thesesurfactants are also relatively inefficient during the particlenucleation stage of polymerisation.

[0004] The present invention adopts a different approach to enablingpolymerisation at desirable higher temperatures by using anionicallymodifying conjugated unsaturated fatty alcohol ethoxylate surfactants.Such anionically modified surfactants can be used at temperaturessignificantly higher than is possible using the unsaturated fattyalcohol moderate ethoxylates of the prior art without the molecularweight penalty and other disadvantages of very high ethoxylates. Theyare also very efficient during particle nucleation, including atelevated temperatures e.g. 60 to 100° C., thus enabling the manufactureof product polymers with particles having a controlled smaller particlesize without requiring the use of other surfactants especially at theparticle nucleation stage. We believe that the anionically modifiedsurfactants are to a large extent covalently grafted into the productpolymer and latices made with these polymers have improved waterresistance against blushing and absorb less water than conventionalproducts.

[0005] Accordingly, the present invention provides a method of freeradical initiated addition polymerisation of at least one ethylenicallyunsaturated monomer in which the dispersed phase is stabilised by asurfactant including at least one anionic surfactant compound of theformula (1):

R¹-(OA)_(n)-X  (I)

[0006] where

[0007] R¹ is a C₁₆ to C₂₂ hydrocarbyl group including at least twodouble bonds;

[0008] OA is an oxyalkylene group;

[0009] n is from 2 to 60, desirably 5 to 30; and

[0010] X is a group including at least one acidic H atom, or a saltthereof.

[0011] The method of this invention is particularly applicable toemulsion polymerisation, especially the oil-in-water emulsionpolymerisation of ethylenically unsaturated monomers. In particular, themethod is applicable to the polymerisation of systems using or includingacrylic monomers and/or vinyl monomers, particularly in oil-in-wateremulsion polymerisation. These form particular aspects of the invention.

[0012] The group R¹ is a C₁₆ to C₂₂ hydrocarbyl group including at leasttwo double bonds. In particular it is a C₁₈ or C₂₀ unsaturatedhydrocarbyl group such as an unsaturated alkyl group. Desirably, atleast two of the double bonds are conjugated, and in particular thegroup R¹ includes two double bonds and these double bonds areconjugated. Particularly desirable groups R¹ are of the formula:

R² —(—CH═CH—CH═CH—)—R³  (II)

[0013] where

[0014] R² is a C₁ to C₈ alkyl group, particularly a group CH₃.(CH₂)₁where 1 is from 0 to 7; and

[0015] R³ is a C₄ to C₁₂ alkylene group particularly a group (CH₂)_(m)where m is from 4 to 12.

[0016] In this case the compound of the formula (1) is of the formula(1a):

R²—(—CH═CH—CH═CH—)—R³—(OA)_(n)—X  (1a)

[0017] where R², R³, OA, n and X are as defined above.

[0018] The desirably conjugated, double bond system is preferably notterminal in the overall hydrocarbyl group. In particular, referring tothe formula (II), the group R² desirably contributes chains of at least2 carbon atoms, more usually at least 3 and preferably at least 4 carbonatoms to the overall hydrocarbyl chain; correspondingly 1 is desirablyat least 2 and preferably at least 3. We have obtained good results whenthe group R¹ is the residue of an alcohol, R¹OH, which is desirably aconjugated isomer of linoleyl alcohol. These residues are residues ofthe formula (II) in which R² is n-pentyl or n-hexyl (1=4 or 5) and R³ iscorrespondingly n-nonyl or n-octyl (m=9 or 8), derived from whichever ofthe two double bonds in linoleyl alcohol:CH₃(CH₂)₄.CH═CH.CH₂.CH═CH.(CH₂)₇CH₂OH moves to form a conjugated system.The residues can be derived from the corresponding alcohol which can bemade by rearrangement e.g. under strong base catalysis, and the alcoholused in the synthesis of the surfactant or the residues can be made insitu by allowing the rearrangement to take place during surfactantsynthesis e.g. under alkali catalysis during alkoxylation of linoleylalcohol. When derived from linoleyl alcohol in this way the product willbe a mixture of compounds with the two conjugated unsaturation patterns,typically containing approximately equal amounts of each compound. Otherdoubly unsaturated residues can be made from corresponding naturalsource materials by similar methods. Other potential double unsaturatedderivatives include alkoxyiates of abietyl alcohol (the alcohol derivedfrom reduction of the carboxyl group in abietic acid; systematicallynamed as1,2,3,4,4a,5,6,10,10a-decahydro-1,4a-dimethyl-7-(1-methylethyl)-1-hydroxymethyl-phenanthrene).

[0019] Typically, when alcohols derived from natural sources are used,the doubly unsaturated material will be available in mixture with othersimilar compounds having different levels of unsaturation. Mixtures ofdoubly unsaturated alcohol residues with singly unsaturated residues andeven proportions of saturated residues can be used. Generally it isdesirable that the proportion of multiple, especially double,unsaturated R¹ residues is at least 15 mole %, desirably at least 40mole %, and preferably at least 50 mole %. Typical commerciallyavailable double unsaturated materials contain from 40 to 65 mole°/acommonly about 50%, double unsaturated residues. Such materials can beused satisfactorily in this invention. Materials having higher levels ofdouble unsaturated residues may provide additional benefits but aresignificantly more expensive.

[0020] The group X is a group including at least one acidic H atom or asalt thereof, by which we mean that the group X can be ionised to forman anionic group in an aqueous medium. In use the group X functions toprovide an anionic function making the surfactant an anionic surfactant.The anionic functionality can be provided by a phosphorus acid group, asulphur acid group or a carboxylic acid group. Suitable phosphorus acidgroups include phosphate: —O—P—(O)(OH)₂ and monoester phosphate—O—P—(O)(OR⁴)(OH), where R⁴ is an ester forming group, typically a groupof the formula R¹—O—(OA)_(n)—, where R¹, OA, and n are as defined abovefor formula (1) and is usually the same as the other groupR¹—O—(OA)_(n)— defined in formula (I), sulphur acid groups includesulphate: O—S—(O)₂—OH, sulphonate: —R⁵—S—(O)₂—OH, where R⁵ is a C₂ to C₆alkylene group, particularly a —C₃H₆— group or a —C₂H₄— group (giving Xas an isethionate: —C₂H₄—S—(O)₂—OH group), and suitable carboxylic acidgroups include carboxymethoxy: —O—CH₂—CO₂H, maleate: ═O—(O)C—CH═CH—CO₂H,succinnate: —O—(O)C—CH₂—CH₂—CO₂H and sulphosuccinate—O—(O)C—[C₂H₃(SO₃H)]—CO₂H.

[0021] When the anionic functionality is provided by a phosphorus acidgroup, it is generally desirable that the surfactant contains a highproportion, in particular at least 50%, more usually at least 60% andespecially at least 65°/a, of the surfactant is of the formulaR¹—(OA)_(n)—O—P—(O)(OH)₂ where R¹, A and n are as defined in formula (I)i.e. a phosphate ester having one unsaturated alcohol residue.

[0022] The anionic group can be introduced into the molecule by methodsgenerally known in the art.

[0023] Mostly these are by reaction of a compound R¹—O—(OA)_(n)—OH withsuitable reactive anionic compounds. For example, compounds where X isphosphate or ester phosphate can be made by reaction of a compoundR¹—O—(OA)_(n)—OH with polyphosphoric acid, phosphorus pentoxide,oxychloride or trichloride. The reaction produces a statistical mixtureof mono-, di- and tri-ester products and the proportions can becontrolled to increase the proportion of the desired compound by varyingthe proportions of the starting materials. Sulphates can be made byreacting a compound R¹—O—(OA)_(n)—OH with sulphuric acid and sulphonatesby reacting such a compound with an hydroxyalkylenesulphonate e.gisethionic acid, or where R⁵ is a 1,3 propylene group with propylenesultone. Carbomethoxy end groups can be provided by reaction of thealkoxylated alcohol with a-haloacetic acid or an acrylate ester undersuitable conditions or by controlled oxidation of the terminal ethoxygroup in a polyethoxylate. Maleate and succinate end groups can beprovided by esterification reactions with the corresponding anhydrideand the sulphosuccinate by onward reaction of the maleate ester productwith sodium bisulphite.

[0024] The salt forming moiety, when present, can be alkali metal,particularly Li, Na or K, ammonium, including amine orhydroxy-substituted amine e.g. alkanolamine, onium, or amine,particularly alkylamine, especially tertiary alkylamine andhydroxy-substituted amine e.g. alkanolamine, especially tertiaryalkanolamine such as triethanolamine. Salts can generally be made fromfree acid precursors by direct reaction with an appropriate base.

[0025] The oxyalkylene group OA is usually a group of the formula:—(OC_(m)H_(2m))— where m is typically 2, 3 or 4, desirably 2 or 3, i.e.an oxyethylene or oxypropylene group. The polyoxyalkylene chain may bewholly of oxyethylene residues or, less generally desirably, wholly ofoxypropylene residues, or it may include both oxyethylene andoxypropylene residues to give a random or block copolymer chain.Generally, it is desirable that the chain is a homopolymericpolyoxyethylene chain.

[0026] The value of n will generally be chosen to provide the desiredproperties in the intended product. Typically, where the polyoxyalkylenechain is a polyoxyethylene chain it will usually have 2 to 60, moreusually 5 to 30 oxyethylene residues and where it is a polyoxypropylenechain it will usually have 2 to 30 oxypropylene residues. Where thechain is a block or random copolymer of oxyethylene and oxypropyleneresidues the chain length chosen will typically correspond to the aboveranges but numerically according to the proportion of oxyethylene andoxypropylene residues in the chain. In copolymer chains usuallyoxyethylene residues will provide at least 50 mole % of the totaloxyalkylene residues. Oxybutylene residues can be included in the chain,but when present these will usually be present as a minor component ofthe chain e.g. up to about 20 mole % of the total polyoxyalkylene chain.

[0027] Of course, numerical values of numbers of repeat units in thepolyoxyalkylene chain are average values. As is common to surfactantscontaining a polyoxyalkylene chain, the higher the proportion ofoxyethylene residues, and the longer the polyoxyethylene chain, and themore hydrophilic the product.

[0028] The ethylenically unsaturated monomers that can be polymerisedinclude unsaturated carboxylic acids and their alkyl esters, amides,N-substituted amides and nitrites, aromatic vinyl compounds, dienecompounds which may be included as monomers or specifically ascrosslinking agents, vinylethers, vinylesters, olefines and hydrophobicallyl compounds.

[0029] Unsaturated carboxylic acids and their derivatives includeacrylic species including alpha alkyl, especially methyl species, suchas (meth)acryiic acid and (meth)acrylate esters including alkyl andhydroxyalkyl (meth)acrylates, such as methyl methacrylate and vinyl(meth)acrylate; acrylonitrile and methacrylonitrile; and water insoluble(meth)acrylamides such as acrylamide, N-isopropylacrylamide andN-methylol(meth)acrylamide; including cationic and quaternary species;alkanediol (meth)acrylates such as (poly)ethyleneglycoldi(meth)acrylates and methoxypolyethylenegtycol (meth)acrylates,urethane acrylates and epoxy acrylates; fumaric acid, maleic acid andanhydride and itaconic acid and their esters, particularly dialkylmaleates, dialkyl fumarates, dialkyl itaconates, amides and imides.

[0030] Vinylic species include halides such as vinyl halides, especiallyvinyl chloride, and vinylidene halides, especially vinyfdene chloride,vinyl esters such as vinyl acetate, vinyl propionate and higher linearand branched acid esters, vinyl ethers. Aromatic vinyl compounds includestyrene, a-methy(styrene and p-tert-butylstyrene and vinyl pyridines.Other ethylenically unsaturated monomers include olefins particularya-olefines such as ethylene, propylene and butene and diene compoundsinclude butadiene, isoprene, isobutadiene chloroprene and divinlbenzene.

[0031] The polymerisation can be carried out to make homopolymers suchas poly(vinyl acetate), polystyrene and poly(methyl methacrylate) orcopolymers such as ethylene-vinyl acetate copolymers, acrylic copolymersand styrenelacrytic copolymers, styrene-butadiene rubbers andcarboxylated styrene-butadiene rubbers, butadiene-acrylonitrife rubbersand chlorinated polymers such as polychloroprene.

[0032] The invention is particularly applicable to the manufacture ofacrylic copolymers, for example those where at least 50%, more usuallyat least 60%, desirably at least 80°/a e.g. 90% or more up to 100%, byweight of the monomers are acrylic monomers. The method carried outusing acrylic monomers forms a specific aspect of the invention. Theacrylic polymers may be those based on mixed alkyl acrylates, especiallywhere the predominant monomer is methyl methacrylate, which copolymersmay include anionic units such as (meth)acrylic acid units or cationicunits such as amino substituted ethylenically unsaturated monomers suchas allyl amine and dially(dimethylammonium chloride.

[0033] The amount of surfactant used will depend on the particularmonomers used and the polymerisation system used, the degree ofcolloidal stability needed and the desired particle size of the polymerin the product latex. However, for an otherwise conventionalwater-in-oil emulsion polymerisation, to give a latex having a particlesize of from 80 to 500 nm the amount of surfactant used will typicallybe from 0.25 to 5 parts by weight surfactant per 100 parts by weighttotal monomer (phm). More usually the amount will be from 0.5 to 2.5phm, particularly from 1 to 2 phm.

[0034] In microemulsion polymerisation systems, the concentration ofmonomer is typically substantially lower than in conventional emulsionor other dispersion polymerisation systems e.g. from 3 to 10°/a byweight. The proportion of surfactant relative to the amount of monomeris also relatively high because the microemulsion has higher interfacearea per unit mass of monomer corresponding to the smaller emulsionparticle size. Typical surfactant levels can be from 10 to 150 phm.Overall the solids content of microemulsion systems are usually in therange 15 to 30% by weight of the total emulsion.

[0035] Desirably, the compounds of the formula (I) are used as the solesurfactant emulsifier in the polymerisation process of this invention.Of course, mixtures of compounds of the formula (I) e.g. differing inthe nature of the group R¹, the nature and length of the polyoxyalkylenechain or the nature of the anionic group can be used as can mixtureswith the non-ionic alkoxylated unsaturated alcohol precursors,particularly to tailor the properties of the end product polymer. Ifdesired minor amounts of conventional anionic, cationic or non-ionicsurfactants may be used. In this context, the presence of ‘conventional’materials derived from components of R¹ [in formula (I)) in thesynthetic raw materials which do not have multiple unsaturation is notconsidered as adding conventional surfactants.

[0036] The polymerisation catalyst in the process in general may be anyconventional free radical polymerisation initiator for ethylenicallyunsaturated systems and in particular for emulsion polymerisationsystems. Examples include peroxidic compounds such as inorganicper-compounds e.g. potassium persulphate, and organic per-compounds e.g.tertiary butyl hydroperoxide and other free radical generators such as2,2′-azobisisobutyronitrile. The proportion of catalyst used willtypically be from 0.001 to 10% by weight, and more usually from 0.01 to7%, based on the total monomer. When a redox couple is used as theinitiator, the proportion of reducing agent is typically from 0.05 to100 mole %, more usually 0.1 to 80%, based on the molar amount ofpolymerisation initiator.

[0037] Other additives in the reaction system can include chain transferagents, such as alkyl mercaptans and similar acting compounds typicallyincluded at from 0 to 5 phm, more usually from 0.1 to 1 phm;crosslinking agents, such as divinyibenzene or ethylene glycoldimethacrylate, typically used to modify the product polymer molecularweight, at typical concentrations of from 0 to 5 phm, more usually from0.1 to 1 phm; water soluble polymers e.g. hydroxyethylcellulose,carboxymethyl-cellulose, polyethyleneglycot and partially hydrolysedpolyvinylacetate, typically used to modify the viscosity of the system,included at concentrations from 0 to 10 phm, more usually from 0.1 to 2phm; buffers for pH control, sequestering agents, electrolytes andorganic solvents in minor amounts totalling typically from 0 to 5 phm,more usually from 0.1 to 3 phm.

[0038] The polymerisation reaction can be carried out using generallyconventional procedures typically at temperatures in the range fromambient temperature to 100° C., usually 60 to 100° C., desirably from 70to 95° C. e.g. commonly about 85° C. It is an advantage of thesurfactants of the formula (I) used in this invention that they areeffective at such elevated temperatures.

[0039] The polymerisation process of this invention, particularly as anemulsion, especially an oil-in-water emulsion, polymerisation, can becarried out over a wide pH range for example 3 to 11, particularly 4 to10, but more usually at moderately acid pH e.g. 3 to 6, especially 4 to5. After completion of polymerisation, the resultant polymer latices maybe neutralised, typically to a pH of 7 to 10 using organic bases e.g.amines or alkanolamines, or inorganic bases e.g. alkali metal hydroxidesor carbonates.

[0040] Polymerisation reactions can be carried out in a closed kettleequipped with heating and cooling devices, agitation, thermometer,condenser and inlets for inert gas, monomers and initiator streams. Allformulation ingredients can be charged to the reactor from the start inwhat is known in the art as a batch process. The preferred productionprocess used when working with compounds of the present invention is asemi continuous mode. Part of the ingredients are charged to thereactor, the rest is gradually fed into the reactor in single ofmultiple feed streams. Monomers are fed as a neat monomer stream, or aremixed into a part of the water with a part of the surfactants andoptionally other additives to form a pre-emulsion. Monomer compositioncan change during the feed stage to control particle morphology.

[0041] The latices synthesised by the method of this invention havelower levels of free surfactant species than products made usingconventional surfactants that are not non-migratory. This yieldsend-products that can have improved resistance to water, highercolloidal stability, show better adhesion to substrates and otheradvantages related to reduced levels of free surfactant.

[0042] The product polymers obtained by the method of this invention canbe used as binders or film formers in interior and exteriorarchitectural coatings, floor coatings, paper and paperboard coatings,coatings for metal protection, waterborne adhesives, inks, binders fornon-woven fabrics, concrete and cement additives. Latices can beformulated as such in formulations where water is the carrier, or thepolymer can be separated from the aqueous phase by flocculation, spraydrying or other known techniques.

[0043] The following Examples illustrate the invention. All parts andpercentages are by weight unless otherwise stated.

[0044] Materials

[0045] CS1 ‘conjugated linoleyl alcohol’ 12-ethoxylate made as describedin WO/13849 A (based on

[0046] Ocenol 1101130 linoleyl alcohol with an Iodine value from 110 to130) The following products were made from CS1 as described below:

[0047] S1 neutralised mono-phosphated ‘conjugated linoleyl alcohol’10-ethoxylate.

[0048] S2 neutralised di-phosphated ‘conjugated linoleyl alcohol’110-ethoxylate.

[0049] S3 mono-phosphated ‘conjugated linoleyl alcohol’ 6-ethoxylate.

[0050] S4 mono-phosphated ‘conjugated linoleyl alcohol’ 12-ethoxylate.

[0051] S5 mono-phosphated ‘conjugated linoleyl alcohol’ 20-ethoxylate.

[0052] S6 mono-phosphated ‘conjugated linoleyl alcohol’ 30-ethoxylate.

[0053] Water—Demineralised water purged with nitrogen for 15 minutesbefore use

[0054] KPS potassium persulphate free radical polymerisation initiator

[0055] Test Methods

[0056] Viscosity—was measured with a Brookfield RV viscometer usingspindle 4 at a speed of 100 rpm (ca 1.7 Hz). Results are given as “Visc”in mPa.s

[0057] Surface Tension—was measured by the Wilhelmy Plate method withresults as “ST” in mN/m.

[0058] Particle size—was measured with a Malvern Zetasizer. TheZ-average particle size is given as “Z-Ave” in nm and volume averagepartite size as V-ave in nm.

[0059] wet grit—was measured by filtration of latex through a sieve withthe result given as the weight % of wet grit based on total latexsolids—sieves of 240 μm and 80 μm were used.

[0060] Foaming—was measured using the Ross Miles foam test on 0.5% byweight aqueous surfactant solutions or on the latex diluted to 5% solidsand results are given as RM Foam Height after 0, 5 and 10 minutes.

[0061] Shear Stability—was assessed by subjecting the latex to highshear stirring using a slotted circular paddle stirrer with verticalperipheral extensions at ca 3000 rpm (50 Hz).

[0062] Freeze Thaw Stability (FT Stab)—was assessed as the number of 24hour cycles between −20° C. and 23° C. (12 hours at each temperaturethat the neutralised test latex withstands without breaking.

[0063] Water Spotting (Spot)—was assessed by placing a spat of water ona film made using the latex and ranking the extent to which the film iswhitened; 0=complete film whitening and 10=film unaffected. Forcomparison a film made from a latex polymerised using (saturated)stearyl alcohol 10-ethoxylate mono-phosphate as the surfactant scores 1on this test.

[0064] Contact angle (degrees)—was measured at 1, 5 and 11 minutes afterplacing a drop of water on a latex film of 150 nm wet thickness dried at40° for 7 days.

[0065] Bloom—was measured by immersing a latex film, 150 nm wetthickness dried at 40°, in water and measuring the °/a haze initially(OH), after 2 hours (2H), 1 day (1 D) and 1 week (1 W) immersion.

[0066] Water uptake (°/a) was measured by immersing a. latex film, 150nm wet thickness dried at 40°, in water and measuring the % water uptakeafter 1 day (1 D), 5 days (SD) and 2 weeks (2W) immersion.

[0067] Synthesis of Phosphated Surfactants

[0068] S1-‘Conjugated Linoleyl Alcohol’ 12-Ethoxylate Mono-Phosphate

[0069] Conjugated linoleyl alcohol 12-ethoxylate CSI (400 g; MW719.2—calculated from the hydroxyl value of the ethoxylate; 0.56 mole)was charged under a nitrogen blanket at ambient temperature to a 1 litre4-necked round bottom flask equipped with an overhead stirrer, nitrogenblanket adaptor, thermometer, heating mantle and a 500 ml stopperedKontes powder addition funnel containing powdered P₂O₅ (39.5 g; 0.28mole). The Kontes funnel included a grooved PTFE auger shaft in theoutlet tube to control addition of the powder and a small bore tube andwith tap to equalise pressure around the main addition tap. The funneloutlet led towards the flask centre to minimise accumulation on theflask walls. The CS1 was heated to 75° C. under stirring at 400 rpm (ca6.7 Hz). Water (3.6 g) was added to increase the total amount of waterin the reaction medium to 1 mole and P₂O₅ was added stepwise through theKontes funnel so that the reaction exotherm raised the temperature to amaximum of 100° C. After completion of the P₂O₅ addition, the reactionmixture was heated to 140° C., held at this temperature for 1.5 hoursand then cooled to 100° C. Water (21.6 g) was added to bring the totalwater content to 5% by weight, the mixture held at 100° C. for 0.5 hoursand then cooled to ambient temperature. The results of NMR analysis areset out in the Table below. The calculated molecular weight of theproduct using the monoldi-ester ratio from the NMR analysis was 1065.The phosphoric acid ester was neutralised using ammonia (25°/a; ca 13°/aby weight based on the product) and the mixture further diluted withdemineralised water to give a 10°/a by weight active surfactant solutionwith a pH of 6.8, after equilibrating overnight. This surfactantsolution was used in the Examples as the source of surfactant S1.

[0070] S2-‘Conjugated Linoleyl Alcohol’ 12-Ethoxylate Di-Phosphate

[0071] Conjugated linoleyl alcohol’ 12-ethoxylate CS1 (143.8 g; MW719.2; 0.2 mole) was charged under a nitrogen blanket at ambienttemperature to a flask set up as described above for making themono-phosphate. The alcohol was dewatered under vacuum (7 mm Hg; ca 130Pa) for 1 hour under stirring (400 rpm; ca 6.7 Hz), the vacuum wasreleased and the mixture cooled to 70° C. P₂O₅ (8.5 g; 0.06 mole) wasadded stepwise through the Kontes funnel over a period of 25 minutes.The reaction mixture was then heated to 140° C., held at thistemperature for 3 hours and then cooled to 900° C. Water (9.0 g) wasthen to bring the total water content to 5% by weight, the temperatureheld at 100° C. for 0.5 hours and the mixture was then cooled to ambienttemperature. The product was neutralised with ammonia (ca 7% by weight)and diluted generally as described for S1 and the resulting solutiondesignated S2.

[0072] The method described for making S1 was also used to make S3 andS4 containing 6 and 12 EO residues respectively but S5 and S6 containing20 and 30 EO residues respectively the following method usingpolyphosphoric acid rather than phosphorus pentoxide was used:

[0073] S6-‘Conjugated Linoleyl Alcohol’ 20-Ethoxylate Mono-Phosphate

[0074] Conjugated linoleyl alcohol 20-ethoxylate (341 g; 0.325mole—based on a MW of 1049 calculated from the hydroxyl value of theethoxylate) was charged under a nitrogen blanket at ambient temperatureto a 500 ml round bottom flask equipped with a pressure equaliseddropping funnel, agitator, nitrogen blanket adaptor (0.2 ml nitrogen perminute through the flask during the reaction), thermometer,thermostatically controlled heating mantle and a horizontal condenser toa receiver. The ethoxylate was heated to 80° C. to melt it and thenpolyphosphoric acid (technical grade—84.53% P₂O₅, 42.0 g; equivalent to0.25 mole P₂O₅) was gradually added keeping the temperature in the range80 to 100° C. After completion of the polyphosphoric acid addition, thereaction mixture was heated to 140° C., held at this temperature for 3hours and then cooled to 90 to 100° C. Water was added to bring thetotal water content to 5% by weight, the mixture held at 100° C. for 0.5hours and then cooled to ambient temperature. This surfactant solutionwas used in the Examples as the source of surfactant S6. Surfactant S7was made by a similar process but substituting conjugated linoleylalcohol 30-ethoxylate for the 20-ethoxylate material.

[0075] Analysis data on anionic surfactants made by the methodsdescribed above and their properties are summarised in the table below:Analysis (% by wt) Code EO No H3PO4 Mono Di Tri Poly Pro Free Alcohol S110 2.2 62 32 1.6 0.1 2.5 S2 10 0.4 36 60 ND 0.2 4.3 33 6 3 67 27 ND <0.13 S4 12 2.7 69 24 ND 0.1 4.2 S5 20 5.6 75 14 ND 0.1 5.5 S6 30 4.6 79 15ND 0.4 1.9

[0076] Surface Tension (given against Log[surfactant concentration in wt%]) and RM Foam Height at 0.5% surfactant in water for anionicsurfactant S4: Surface Tension RM Foam Height Surfactant 0 −1 −2 −3.3 05 10 S3 3 2.5 2 S4 34.3 36.5 38.2 49.2 12 11.8 10.3 S5 40.0 40.8 44.047.0 10.8 7 6

EXAMPLE 1

[0077] Batch Emulsion Polymerisation

[0078] Batch polymersations were carried out at low solids (10%) tosimulate the conditions during the seed stage of a semi-continuousemulsion polymerisation to provide an evaluation of surfactantefficiency during particle nucleation. Batch recipe: Material (parts bywt) Monomers: (% by wt) 100 BA 48.8 MMA 49.9 MAA 1.3 PotassiumPeroxidisulphate 0.3 Sodium bicarbonate 0.1 Water 15 S1 variable* Waterto 1000

[0079] The Z-average particle size of the polymer particles was measuredusing a Malvern Zetasizer 4 (photon correlation spectroscopy) with thedetector at 90°. Z-average article size Run S1 amount size No (phm) (nm)1.1 0.5 86.4 1.2 0.9 76.8 1.3 1.6 61.2 1.4 2 61.2

EXAMPLE 2

[0080] Three BA/MMA/MAA (48.8149.911.3 by wt) latices at 45% solids weremade by semi-continuous emulsion polymerisation. Two were made usingsurfactant S1 (Runs 1 and 2) and one, for comparison, using surfactantCS1 (Run 3). The surfactant concentration in the starting emulsion waschosen to give a desired number of particles in the initialpolymerisation stage (when using surfactant S1) so as to yield a finallatex particle size of 150 nm. The level was calculated from the amountof surfactant used and final particle size distribution in Example 1.The total surfactant concentration was varied from 1.05 to 1.81 phm.Materials For each run four feed mixtures were made up: Run 1 Run 2 Run3 1 Starting emulsion Water 510.9 510.9 510.9 Monomers 61.1 61.1 61.1Surfactant solution (10%) 9.8 9.8 9.8 2 Start initiator KIPS 0.2 0.2 0.2Na bicarbonate 0.06 0.06 0.06 Water 20 20 20 3 Main monomer feedMonomers 838.9 838.9 838.9 Surfactant solution (10%) 153.1 85 153.1Water 343.7 411.8 343.7 4 Feed initiator KIPS 1.7 1.7 1.7 Na bicarbonate0.6 0.6 0.6 Water 60 60 60 Total 2000 2000 2000

[0081] Production Method

[0082] The reactor was a jacketed 2 litre 4 necked round bottom glassflask equipped with an overhead stirrer, thermometer, condenser andsupplementary inlets for nitrogen and feed streams.

[0083] 1. The monomer pre-emulsion was made up by emulsifying themonomer phase in a mixture of the surfactant solution and Water understirring with a paddle stirrer at 400 rpm (ca 6.7 Hz);

[0084] 2. the starting emulsion was made in the reactor by charging thewater, surfactant and part of the monomer, at a surfactant level to giveabout 2.3×10¹⁷ polymer particles;

[0085] 3. the reactor was heated to 85° C. under stirring and the firstpart of the initiator was added and the reaction was allowed to proceedfor 15 minutes under a nitrogen blanket;

[0086] 4. the remainder of the monomer emulsion and initiator feed werefed to the reactor simultaneously in two separate streams over a periodof three hours;

[0087] 5. the reactor was kept at polymerisation temperature for afurther 90 minutes, then cooled to 30° C.; and

[0088] 6. the product emulsion was filtered sequentially through filterswith pore sizes of 240 μm and 80 μm and then stored in a bottle. EXAMPLE2 Semi-continuous polymerisation Results Run 1 Run 2 Run 3 Grit >240 Nm(g; wet weighed) 0 0.13 18.5 Grit 80-240 pm (g; wet weighed) 1.7 1.6n.d. Coagulum (g; wet weighed) 0 0 4  Volume average particle size (Nm)146.6 144.8 421.9/706.6*

[0089] These data show that the non-ionic ethoxylated ‘conjugatedlinoleyl alcohol’ surfactant CS1 was not efficient during the particlenucleation stage of polymerisation using normal amounts of surfactant.The product latices made using the phosphate ester surfactant S1, aswell as providing efficient action during particle nucleation, showedbetter stability during polymerisation resulting in lower levels ofmacrogrit and coagulum. The latex stabilised with CS1 sedimented afterstorage over a week end, probably because of its large particle size. Noattempt was made to redisperse the sedimented layer prior to samplingfor particle size analysis and for this reason, the microgrit level wasnot determined.

EXAMPLE 3

[0090] The batch polymerisation described in Example 1 was re-run usingvarious amount of surfactant S4 instead of the surfactant S1 used inExample 1. The Z-average particle size (in nm) of the latices wasmeasured and the results are set out in the table below: amount ofsurfactant (phm) 0.5 0.9 1.6 2 5 10 neutralised S4 86.4 76.8 61.2 61.2non-neutralised S4 73.9 65.1 47.7 NPE6* 101.1

[0091] These data indicate that even when not neutralised, surfactant S4is more efficient than the conventional anionic surfactant inemulsifying the monomer. Further data are given in Tables 1, 2 and 3below.

EXAMPLE 4

[0092] Four co-polymer acrylic latices were made by the generalsemi-continuous method described in Example 2 using anionic surfactantS4. The target latex polymer particle size was 150 nm, the latex polymersolid yield 450 g, the target number of polymer particles 2.3.10¹⁷, andthe monomers used were butyl acrylate, methyl methacrylate andmethacrylic acid at base ratios of BA/MMA/MAA of 48.8/49.9/1.3. For someruns, the overall percentage of MAA was reduced to 0.5%, with theamounts of BA and MMA adjusted to compensate keeping the ratio of BA toMMA constant. The proportions used are included in Table 1, LatexParticle Size, Shear Stability and Freeze Thaw Stability data areincluded in Table 2 and water uptake testing data is given in Table 3.For each run four feed mixtures were made up: 4a 4b 4c 4d 1 Startingemulsion Water 236.3 236.3 236.3 236.3 Monomers 29.8 29.8 29.8 29.8Surfactant solution (20%) 7.45 7.45 7.45 7.45 2 Start initiator KPS 0.090.09 0.09 0.09 Na bicarbonate 0.04 0.04 0.04 0.04 Water 10 10 10 10 3Main monomer feed Monomers 420.2 420.2 420.2 420.2 Surfactant solution(10%) 26.4 49.4 71.5 49.4 Water 225.6 201.7 180.45 202.5 4 Feedinitiator KPS 0.84 0.84 0.84 0.84 Na bicarbonate 125 1.25 1.25 0.4 Water30 30 30 30 t-butyl hydroperoxide (70%) in 0.23 0.23 0.23 0.23 Water 5 55 5 Na formaldehyde sulfoxylate in 0.18 0.18 0.18 0.18 Water 7.5 7.5 7.57.5 Total 1000 1000 1000 1000

EXAMPLES 5 AND 6

[0093] Runs similar to Example 4 were carried out using anionicsurfactant S4 at 0.33 phm in the starting emulsion (1) and S5 (Example5) and S6 (Example 6) in the main monomer feed (3). The proportions usedare included in Table 1, Latex Particle Size, Shear Stability and FreezeThaw Stability data are included in Table 2 and water uptake testingdata is given in Table 3. TABLE 1 Process Variables and Latex PropertiesRM Foam MAA Z-ave wet grit Visc Height Ex No (%) Surf. (phm) (nm) pH S T(mN/m) (%) (mPa · s) 0 5 10 3a 1.3 1.5 141.3 110 4.5 2 0.5 3b 1.3 2.5143.7 2.8 130 7.5 6.5 6 3c 0.5 2.5 1442 2.8 110 9 9 8 4a 1.3 1.5 142.46.02 0.01 60 3 0.5 4b 1.3 2.5 143.1 3.15 46.8 0.02 90 9.9 9.5 9 4c 1.33.5 145.8 2.75 48.2 0.02 130 10.8 9 5.5 4d 0.5 2.5 145.3 3.66 44.4 0.0490 10 5.5 4 5a 1.3 1.5 140.1 2.8 0.04 6 2 1.5 5b 1.3 2.5 142.5 2.7 0.0180 7.5 5 3.5 5c 0.5 2.5 143.2 2.9 0.4 100 6a 1.3 1.5 142.9 3.6 0.23 653.5 0.5 0.5 6b 1.3 2.5 143.7 3.4 130 4 3.5 3.5 6c 0.5 2.5 141 3.7 0.02120 5.5 3.5 1.5

[0094] TABLE 2 Latex Testing Particle Size Shear Stability and FreezeThaw Stability (FT Stab) non-neutr latex Shear Stab Ex Z-ave Vol-aveZ-ave Vol-ave FT Stab No (nm) (nm) (nm) (nm) neutr 3a 141.3 137.5 146.7139.5 5 3b 143.7 138.4 143.4 132   5 3c 144.2 133.3 144.5 132.3 — 4a142.4 127.1 — — 5 4b 143.1 135.2 142.7 135.9 5 4c 145.8 141.1 144.4136.4 5 4d 145.3 136.5 — — — 5a 140.1 131.2 — — 5 5b 142.5 130.5 170  155   5 5c 143.2 136.6 — — — 6a 142.9 135.6 — — 1 6b 143.7 139.2 145.5129   5 6c 141   131.5 — — —

[0095] TABLE 3 Latex film water resistance Testing Contact Bloom Waterangle (% Haze) Uptake (wt %) No Spot 1 min 5 min 11 min OH 2H 1 D 1 W 1D 5D 2W 3a 0.9 2.6 13.3 17 8 13 18 3b 66 63 55 1.9 2.8 6.8 15.5 8 24 253c 66 63 55 0.7 2.3 12 20.7 15 20 33 4a 6 63 62 0.5 2.1 9.2 24.9 10 1515 4b 6 62 62 0.6 1.8 6.8 20.4 10 17 22 4c 65 58 0.6 3.1 18 66.5 10 704d 6 65 59 1.3 3.2 8 22.7 11 13 19 5a 71 65 58 0.3 2.8 13.2 34.9 6 13 5b62 57 50 0.3 3.8 22.5 64 14 24 5c 64 56 49 0.9 6.1 35.2 77.2 12 20 6a 7372 68 0.5 25 54.4 11 16 24 6b 77 71 64 0.7 4.3 22.4 47.2 13 23 32 6c 6964 57 0.4 8.6 48.5 82 12 21 36

1-13. (Cancelled).
 14. An aqueous dispersion of polymeric particleswherein the dispersion is formed in the presence of a stabilizing amountof an anionic alkoxylate surfactant of formula I R′—(OA)_(n)—X whereinR′ is a C₁₆₋₂₂ hydrocarbon chain having two or more double bonds, atleast two of said double bonds being conjugated; OA is selected from thegroup consisting of oxyethylene, oxypropylene and oxybutylene; n is 2 to60; and X is an anionic group having at least one acidic hydrogen, or asalt thereof.
 15. An aqueous dispersion according to claim 14 whereinsaid anionic group is provided by a phosphorus acid group, a sulphuracid group or a carboxylic acid group.
 16. An aqueous dispersion ofpolymeric particles wherein the dispersion is formed in the presence ofa stabilizing amount of an anionic alkoxylate surfactant of formula IR′—(OA)_(n)—X wherein R′ is a C₁₆₋₂₂ hydrocarbon chain having two ormore double bonds, at least two of said double bonds being conjugated;OA is selected from the group consisting of oxyethylene, oxypropyleneand oxybutylene; n is 2 to 60; and X is an anionic group selected fromthe group consisting of acids or salts of phosphate, sulphate,succinate, carboxymethyl, maleate, carboxyethyl, sulphoethyl, andsulfopropyl.
 17. An aqueous dispersion of polymeric particles whereinthe dispersion is formed in the presence of a stabilizing amount of ananionic alkoxylate surfactant of formula I R′—(OA)_(n)—X wherein R′ is aC₁₆₋₂₂ hydrocarbon chain having two or more double bonds, at least twoof said double bonds being conjugated; OA is selected from the groupconsisting of oxyethylene, oxypropylene and oxybutylene; n is 2 to 60;and X is an anionic group selected from the group consisting of acids orsalts of sulphate, succinate, carboxymethyl, maleate, carboxyethyl,sulphoethyl, and sulfopropyl.
 18. An aqueous dispersion according toclaim 14 wherein the dispersion of polymeric particles is prepared byaddition polymerization of an addition polymerizable monomer.
 19. Anaqueous dispersion according to claim 18 wherein the additionpolymerizable monomer is an ethylenically unsaturated monomer.
 20. Anaqueous dispersion according to claim 19 wherein the ethylenicallyunsaturated monomer is selected from the group consisting of C₁-C₁₂alkyl acrylates and methacrylates, methacrylic acid, hydroxyalkylmethacrylate, vinyl acetate, vinyl propionate, styrene, vinyl styrene,vinyl toluene, vinyl pyridine, di-alkyl maleate and vinyl chloride. 21.An aqueous disperison according to claim 14 wherein R′ has the followingstructure: CH₃—(CH₂)_(13-K)—CH═CH—CH═CH—(CH₂)_(K)— wherein K is 8 or 9.22. An aqueous dispersion according to claim 14 wherein R′ is derivedfrom linoleyl alcohol by alkoxylation of said alcohol.
 23. An aqueousdispersion according to claim 14 wherein OA is oxyethylene.
 24. Anaqueous dispersion according to claim 14 wherein OA is oxypropylene. 25.An aqueous dispersion according to claim 14 where X is sulphate,carboxymethyl or a salt thereof.
 26. An aqueous dispersion according toclaim 14 wherein the salt is an amine, ammonium or alkali metal salt.27. A method for preparing an aqueous dispersion of polymeric particlescomprising conducting an addition or condensation polymerization in thepresence of a stabilizing amount of an anionic alkoxylate surfactant offormula I R′—(OA)_(n)—X wherein R′ is a C₁₆₋₂₂ hydrocarbon chain havingtwo or more double bonds, at least two of said double bonds beingconjugated; OA is selected from the group consisting of oxyethylene,oxypropylene and oxybutylene; n is 2 to 60; and X is an anionic grouphaving at least one acidic hydrogen, or a salt thereof.
 28. The methodof claim 27 wherein X is an anionic group selected from the groupconsisting of acids or salts of phosphate, sulphate, succinate,carboxymethyl, maleate, carboxyethyl, sulphoethyl and sulfopropyl. 29.An aqueous dispersion according to claim 14 wherein X is an anionicgroup selected from the group consisting of acids or salts of sulphate,succinate, carboxymethyl, maleate, carboxyethyl, sulphoethyl andsulfopropyl.